CN87100391A - Be particularly suitable for the rolling bearing that the fast mill work roll is used - Google Patents

Abstract

On rolling bearings that are especially suitable for working rolls in high-speed rolling mills, a journal of the roll is supported on two roller bearings to bear radial loads. There are double rows of thrust bearings in between to bear the bidirectional axial load. This rolling bearing enables the journal of the roll to withstand high radial and axial loads when it is slightly inclined. The lines of force of the double row of rolling elements of a thrust bearing are directed radially inward and intersect each other. The rolling body is supported on at least one of the two rolling tracks so that it can move to both sides perpendicular to the rolling direction. The thrust bearing inner ring is radially movable and has a radial clearance relative to the journal that is greater than the rolling clearance of each roller bearing.

Description

Especially suitable for rolling bearings used in high-speed rolling mill work rolls

The present invention relates to a rolling bearing particularly suitable for use with work rolls in high-speed rolling mills. In this case, one of the work rolls is journaled on two roller bearings to support radial loads. The two roller bearings have at least one outer ring and at least one inner ring. A thrust bearing is installed between the two bearings to support axial loads in two directions. The thrust bearing has at least one outer ring and at least one inner ring, and two rows of rolling elements are arranged on the rolling track between the inner and outer rings. The outer rings of the two roller bearings and the thrust bearing are fixed sequentially in the axial and radial directions in a common bore in the rolling mill stand. The inner ring or rings of the thrust bearing, each with a radial end face, rest axially against the end face of the roller bearing inner ring, which is axially and radially fixed to the journal.

Among known rolling bearings is a double-acting axial groove ball bearing thrust bearing, whose outer and inner rings are fixed radially and axially in bores of the rolling mill stand and on the journals of the work rolls, respectively (DE-AS1625610). Due to the inevitable rolling clearance between the two roller bearings, the journals can tilt slightly during operation under torque loads, subjecting the balls in the axial groove ball bearing to uneven circumferential loads. Furthermore, when the work rolls rotate at high speeds, centrifugal forces can cause the balls to move centrifugally from their rolling tracks. Consequently, this known rolling bearing carries the risk of premature failure of the balls in the axial groove ball bearing due to seizure and excessive loads.

Another known rolling bearing incorporates a double-row thrust bearing between two roller bearings to absorb axial loads in two directions (DE-AS2247983). An additional spacer sleeve, radially exceeding the outer ring of the thrust bearing, must be inserted between the two roller bearings. Consequently, this type of rolling bearing is quite expensive to manufacture and assemble. Furthermore, the thrust bearing has two rows of balls, whose lines of force are offset in the radial direction. During operation, when the journal experiences even a slight tilt, these balls absorb a portion of the torque load on the work roll journal and radial loads over a portion of the circumference. This additional radial load on the thrust bearing is particularly detrimental if this type of rolling bearing is used on the journals of high-speed, highly loaded work rolls in a rolling mill.

The present invention is directed to a rolling bearing suitable for use with the work rolls of the aforementioned high-speed rolling mills, characterized in that the lines of force of the two rows of rolling elements of the thrust bearing are directed radially inward and intersect each other; the rolling elements are supported on at least one of the two rolling tracks so as to be movable in both directions perpendicular to the rolling direction; and one or more inner rings of the thrust bearing with end faces are mounted on opposite end faces of the inner ring of the roller bearing and are substantially movable in the radial direction. Furthermore, each inner ring of the thrust bearing has a radial clearance relative to the journal of the work roll that is greater than the rolling clearance of each of the two roller bearings. This bearing, while being capable of withstanding high radial and axial loads, also tolerates slight tilting of the journal of the work roll relative to the mill stand bore during operation. Furthermore, the rolling bearing should be compact, so that the mill stand, along with its associated rolling bearings, can be easily removed from the journal when replacing the rolls.

The structure proposed by the present invention achieves this: Because radial rolling clearance inevitably exists between the two roller bearings, even if the journal tilts within the mill housing, this only results in minimal additional load on the thrust bearing. Specifically, one or more inner rings of the thrust bearing can overcome sliding friction and slide along the axially adjacent inner ring support surfaces. This allows the rolling elements in the rolling tracks of the outer and/or inner rings to experience minimal movement perpendicular to the rolling direction. One of the two rolling tracks in the second row of rolling elements intentionally lacks a lateral guide edge, allowing the rolling elements to move freely laterally within the rolling track.

Since one or more inner rings of the thrust bearing can slide radially relative to the work roll journal between the two roller bearing inner rings, the thrust bearing only bears the axial forces occurring during operation.

In the rolling bearing according to the present invention, the lines of force acting on the two rows of rolling elements of the thrust bearing are directed radially inward and intersect at a point located at least near the centerline of the journal and axially midway between the two rows of rolling elements. Therefore, the journal of the work roll can tilt over a wide range without causing the two rows of rolling elements of the thrust bearing to become stuck in their rolling tracks.

Another feature of the rolling bearing of the present invention is that the two inner rings of the two roller bearings radially fixed on the cylindrical mating surface of the shaft neck and the single or multiple inner rings of the thrust bearing all have an inner hole of approximately the same diameter; the radial clearance of the single or multiple inner rings of the thrust bearing is formed by cutting away a layer of the shaft neck below the single or multiple inner rings of the thrust bearing radially and inwardly relative to the two cylindrical mating surfaces.

This structure allows the entire rolling bearing, along with the mill stand, to be easily removed from the work roll journals if the inner ring of the thrust bearing becomes wedged into its cylindrical mating surface due to sliding wear during operation. This allows the inner ring of the roller bearing on the roll side to pass unimpeded through the radially inward cutout portion of the journal and move axially outward. This ensures that all rolling bearings have the same inner bore diameter, enabling the use of rolling bearings with common overall dimensions.

In the rolling bearing of the present invention, one or more inner rings of two roller bearings and one or more inner rings of a thrust bearing are sequentially arranged on the journal of a work roll. A spindle nut located at the outer end of the shaft supports them against a shoulder of the journal on one side of the roll, and their relative positions in the axial direction are adjustable. With this structure, the inner rings of the entire rolling bearing can be adjusted or readjusted by slightly tightening or creating a small gap between the spindle nut located at the end of the journal.

The rolling bearing of the present invention also includes the following advantageous structures. The inner ring of the thrust bearing can be designed as a monolithic structure, and the rolling surface of the rolling element in the thrust bearing can be designed as a cone; or the rolling surface of the rolling element can be designed as a convex spherical surface (for example, a spherical surface), while the two rolling tracks of the single or multiple outer rings that cooperate with it are concave spherical surfaces, and they have a common spherical center located on the center line of the shaft journal. In addition, lubricating oil grooves are uniformly distributed along the circumference on the inner ring end faces of the two roller bearings that abut the inner ring end face of the thrust bearing, and (or) on the end face of the single or multiple inner rings of the thrust bearing; and radially convex circumference on the inner ring end faces of the two roller bearings that abut the inner ring end face of the thrust bearing, and (or) on the inner ring end face of the thrust bearing opposite the inner ring end face of the roller bearing.

The rolling bearing according to the present invention will be further described by describing two embodiments shown in the following figures.

Figure 1 is a partial longitudinal sectional view of the rolling bearing located on the fixed end of the working roll bearing of the rolling mill;

FIG2 is a partial longitudinal sectional view of an improved rolling bearing located on the fixed end of a working roll bearing of a rolling mill.

In Figure 1, reference numeral 1 denotes a work roll that can be axially adjusted during operation when the mill is rolling hot steel strip. Reference numeral 2 denotes a journal located on the fixed bearing end and operating side of work roll 1. At the other end, on the floating bearing end and drive side, work roll 1 is supported in a well-known manner on a four-row tapered roller bearing (not shown).

The journal 2 is supported in a cylindrical hole 6 of the rolling mill stand. It bears radial loads through two single-row roller bearings 3, 4, between which a double-row thrust bearing 5 is mounted to bear axial loads in two directions.

Each roller bearing 3, 4 has an inner ring 10, 11 fixed to the cylindrical mating surface 8, 9 of the shaft neck 2 and with a cylindrical inner rolling track, and an outer ring 12, 13 fixed in the hole 6 of the rolling mill stand 7 and with a cylindrical outer rolling track. In addition, each has a row of cylindrical rolling elements 14 that roll between the inner and outer rolling tracks.

The thrust bearing 5 consists of an inner ring 15, which typically has two inner rolling tracks, two outer rings 16 and 17, each typically having an outer rolling track, and two rows of tapered rolling elements 18 located between the inner and outer rings. Each row of rolling elements 18 rolls between the inner rolling tracks of the inner ring 15 and the outer rolling tracks of the two outer rings 16 and 17.

In this example, an adjusting ring 19 is installed between the two outer rings 16 and 17 of the thrust bearing 5. The ring has a radially extending lubricating oil hole 20. Lubricant (grease or lubricating oil) is added through the lubricating oil groove on the rolling mill stand 7 and the oil filling hole 20 on the thrust bearing 5.

The outer rings 12 and 13 of the two roller bearings 3 and 4, as well as the outer rings 16 and 17 and adjusting ring 19 of the thrust bearing 5, are axially pressed into the bore 6 of the rolling mill stand 7 and secured with a press fit. This prevents any axial installation forces from acting on the double-row rolling elements 18 of the thrust bearing 5.

By means of the inner end cover 21 (which is fixed to the inner end face of the rolling mill stand 7 with screws 22), the outer rings 12, 13, 16, 17 and the adjusting ring 19 placed in sequence are pressed onto the fixing boss 23 in the hole 6 of the rolling mill stand 7 and axially fixed.

The inner ring 15 has a substantially radially extending end face 24 on each side thereof, which abuts axially against an end face 25 of the adjacent roller bearing 3 or 4 .

The inner rings 10 and 11 of the two roller bearings 3 and 4 and the inner ring 15 of the thrust bearing 5 are fixed to each other on the journal 2. The inner ring 10 of the roller bearing 3 on the roll side is pressed against the radial flange 27 of the work roll 1 in the axial direction through a shoulder ring 26.

At the outer end of the journal 2, a spindle nut 28 is screwed into a hole in a safety face ring 29. This safety face ring is prevented from rotating by a compression spring on the journal. By rotating the spindle nut 28 using an adjusting ring 30, the axial clearance (displacement clearance) between the inner rings 10 and 11 against the inner ring 15 can be finely adjusted. The spindle nut 28 compresses the two-ring support ring 31, which rests against the journal shoulder and is composed of two half rings. This causes the end ring 29 on the journal to move axially toward the inner ring 11. After the axial position of the inner rings 10, 11, and 15 is adjusted, the adjusting ring 30 can be locked in its rotated position using a screw (not shown) that passes through the adjusting ring 30 and screws into a threaded hole in the support ring 31. The support ring 31 is prevented from rotating by a compression spring on the journal 2.

The double-row rolling elements 18 of the thrust bearing 5 have two radially inwardly directed, intersecting force lines 32 and 33. In this embodiment, these lines 32 and 33 intersect near the centerline 34 of the journal 2, i.e., at point 35. This point lies on a radial center plane 36 between the two-way thrust bearings 5.

The tapered outer rolling tracks 37 of the two outer rings 16, 17 of the thrust bearing 5 have no guide edges, so that the rolling elements 18 on the rolling tracks 37 can move freely to both sides perpendicular to the direction of rotation when the inner ring 15 has a small tilted position.

The inner ring 15 of the thrust bearing 5 has a radial clearance 38 relative to the journal 2 within the inner diameter of the inner ring, which is larger than the radial rolling clearance of either of the two roller bearings 3, 4.

In this embodiment, the inner rings 10, 11, which are radially fixed to the cylindrical mating surfaces 8, 9 of the journal 2, and the inner ring 15 of the thrust bearing 5 have the same bore diameter. The radial clearance 38 of the inner ring 15 is formed by cutting away a layer from the underside of the inner ring 15 radially inward relative to the two mating surfaces 8, 9.

Because the gaps between inner rings 10, 11, and 15 are very small, end face 24 of inner ring 15 can slide slightly in the direction of end face 25 of inner ring 10 or 11 (which does not bear axial load), resulting in very small radial displacement within the rolling clearance of roller bearings 3 and 4. Inner ring 15 can move, primarily sliding in the radial direction, particularly on end faces 25 of inner rings 10 and 11, which do not bear axial load.

The end faces 25 of the inner rings 10 and 11 are provided with radially penetrating lubricating oil grooves 39 on their circumferences. These oil grooves can evenly distribute the lubricating oil flowing in from the lubricating oil holes 20 to the end faces 24 sliding on the end faces 25.

In addition, in this embodiment, the end face 24 of the inner ring 15 that slides on the end faces 25 of the inner rings 10 and 11 is slightly ground, so that the end face is slightly convex in the radial direction, so that the lubricating oil can flow more easily between the end faces 25 and 24.

Fig. 2 is an improved rolling bearing, which is similar in structure to the rolling bearing shown in Fig. 1. It also has two single-row roller bearings 3, 4 for bearing radial loads, with a thrust bearing 40 being housed in the middle of the two bearings to bear axial loads.

In this embodiment, the thrust bearing 40 is constructed as a self-aligning roller bearing having a double row of drum-shaped rolling elements 41. It has an integral inner ring 15 and two outer rings 16 and 17 for accommodating the double row of rolling elements 41. Each outer ring is provided with a concave spherical rolling track 42 for accommodating the rolling elements 41.

The force lines 32, 33 of the double row of rolling elements 41, which point radially inward and intersect each other, intersect at a common center 43 of the spherical outer rolling track 42. This center 43 is located on the center line 34 of the journal 2 and on the radial center plane 36 of the thrust bearing 40.

The rolling elements 41 of the thrust bearing 40 are mounted on outer rolling tracks 42 so that they can move in both directions perpendicular to the rolling direction. Therefore, the inner ring 15 of the thrust bearing 40 can rotate around the spherical center 43 during operation, and even slight tilting will not cause the rolling elements 41 to become stuck.

When tilting, the end face 24 of the inner ring 15 can slide on the end faces 25 of the inner rings 10 and 11 opposite thereto - mainly in the radial direction.

At the same time, the inner ring 15 can make a small radial movement of the inner end of its end face 24 relative to the journal 2. However, the inner ring 15 will not contact the journal 2 because there is a radial gap 38 between the inner ring 15 and the journal 2, which is larger than the radial rolling gap of each of the two roller bearings 3 and 4.

The inner rings 10, 11 have some spiral shallow lubrication grooves 44 on their circular bore surfaces. The inner ring 10 of the roller bearing 3 on the roll side rests on a radial shoulder 27 of the work roll 1 with an integral projection 45 extending inwards.

The aforementioned embodiment may be modified in structure within the scope of the present invention. For example, the inner ring of the double-row thrust bearing may be laterally separated so that each row of rolling elements in the double-row ball bearings on the rolling tracks within each inner ring may roll off.

At least one of the two roller bearings may be multi-row. The outer ring and/or the inner ring of the corresponding roller bearing may also be laterally separated so that the rollers of each row can roll on their respective outer ring and/or inner ring.

Claims (9)

1. A rolling bearing particularly suitable for use with work rolls of high-speed rolling mills, wherein one of the work rolls is journaled on two roller bearings to bear radial loads, the two roller bearings having at least one outer ring and at least one inner ring, a thrust bearing being mounted between the two bearings to bear axial loads in two directions, the thrust bearing having at least one outer ring and at least one inner ring, two rows of rolling elements rolling on the rolling track between the inner and outer rings, the outer rings of the two roller bearings and the thrust bearing being fixed sequentially in the axial and radial directions in a common bore of a rolling mill stand, the inner ring or rings of the thrust bearing having radial end faces being axially abutted against the end faces of the inner rings of the roller bearings, which are axially and radially fixed to the journals, such a rolling bearing being characterized by: --The lines of force (32, 33) of the two rows of rolling elements (18, 41) of the thrust bearing (5, 40) are directed inwardly toward the inner diameter and intersect each other. The rolling elements (18, 41) of the thrust bearing (5, 40) are supported on at least one of the two rolling tracks (37, 42) so as to be movable in both directions perpendicular to the rolling direction. - a single or multiple inner rings (15) of a thrust bearing (5, 40) with an end face (24) mounted on the opposite end face (25) of the inner ring of the roller bearing (3, 4) and movable substantially in the radial direction, Each inner ring (15) of the thrust bearing (5, 40) has a radial clearance relative to the journal (2) of the working roll (1), which clearance is greater than the rolling clearance of each of the two roller bearings (3, 4). 2. A rolling bearing according to claim 1, characterized in that the lines of force (32, 33) acting on the two rows of rolling elements (18, 41) of the thrust bearing (5, 40) are directed radially inward and intersect each other at a point (35, 43) located at least in the vicinity of the center line (34) of the journal (2) and axially midway between the two rows of rolling elements. 3. A rolling bearing according to claim 1 or 2, characterized in that the two inner rings (10, 11) of the two roller bearings (3, 4) radially fixed on the cylindrical fitting surfaces (8, 9) of the journal (2) and the single or multiple inner rings (15, 41) of the thrust bearing (5, 40) all have an inner hole of substantially the same diameter, and the radial gap (38) of the single or multiple inner rings (15) of the thrust bearing (5, 40) is formed by cutting away a layer of the journal (2) below the single or multiple inner rings (15) of the thrust bearing (5, 40) inwardly in the radial direction and relative to the two cylindrical fitting surfaces (8, 9). 4. A rolling bearing according to claim 1, 2 or 3, characterized in that: the single or multiple inner rings (10, 11) of the two roller bearings (3, 4) and the single or multiple inner rings (15) of the thrust bearing (5) are arranged in sequence on the journal (2) of the working roll (1) and are supported on the shoulder (27) of the journal (2) on one side of the roll through a shaft head nut (28) located at the outer end of the journal (2), and their relative positions in the axial direction are adjustable. 5. Rolling bearing according to any one of the preceding claims, characterized in that the inner ring of the thrust bearing (5, 40) is designed as a one-piece structure. 6. Rolling bearing according to any one of the preceding claims, characterized in that the rolling surfaces of the rolling elements (18) in the thrust bearing (5) are designed to be conical. 7. A rolling bearing according to any one of claims 1 to 5, characterized in that the rolling surface of the rolling element (41) in the thrust bearing (40) is designed to be convex, for example, spherical, and the two rolling tracks (42) of the single or multiple outer rings (16, 17) that match it are concave, and they have a common center (43) located on the center line (34) of the journal (2). 8. A rolling bearing according to any one of the preceding claims, characterized in that lubricating oil grooves (39) are uniformly distributed along the circumference on the end faces (25) of the inner rings (10, 11) of the two roller bearings (3, 4) resting on the end faces (24) of the inner rings (15) of the thrust bearings (5, 40), and (or) on the end faces (24) of one or more inner rings (10, 11) of the thrust bearings (5, 40). 9. A rolling bearing according to any one of the preceding claims, characterized in that a convex shape is formed in the radial direction of the circumference on the end faces (25) of the inner rings (15) of the two roller bearings (3, 4) which abut against the end faces (24) of the inner rings (15) of the thrust bearings (5, 40), and (or) on the end faces (24) opposite to the end faces (25).

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